(a) Field of the Invention
The present invention relates to an image pickup device suitable especially for endoscopes or the like, which is arranged to use a solid state image sensor to pick up an image of an object formed by an image-forming lens and to perform color display of this image.
(b) Description of the Prior Art
In an image pickup device, in general, using a solid-state image sensor as the image pickup means, the resolution of image is determined by the number of the picture elements (number of the light-receiving elements) which are provided on the image sensor. However, a solid-state image sensor having a large number of picture elements presents not a few problems in its manufacture, and there has been a difficulty in putting to practice the image sensor having a sufficiently large number of picture elements.
In order to solve this problem, therefore, there has been proposed in, for example, Japanese Patent Publication No. Sho 56-40546 an image pickup device which is of a structure representing the so-called "picture element displacement technique" that a plurality of image sensors are arrayed in such a manner as to be shifted in position relative to the optical axis of the image-forming lens by, for example, 1/2 pitch or 1/3 pitch of the interval between the picture elements so that the relative positions of the images on the arrayed picture elements in one image sensor differ from those on the arrayed picture elements of another image sensor, so that the informations corresponding to the sites lying between the picture elements of one image sensor can be picked up also by another image sensor, to thereby enhance the resolving power.
However, in a known device of such a system as mentioned above, it should be noted that, in order to set the amount of displacement of the image at a predetermined value, relative positioning of a plurality of image sensors requires to be effected by displacing them relative to each other, so that there has been the problem that the fabrication of the optical system is very troublesome.